Found in Popular Electronics from the 90s, this circuit is based on a PLL567 and employs high-end or ultrasonic speakers depending on the frequency of oscillations.
This circuit from a 2003 documentation, has a protection system that disarms the power supply if...
This circuit was obtained from an old American documentation, and practically any general-purpose transistor...
In the figure we have the circuit of a sweep generator obtained in an old publication. The central...